1. Field of the Invention
The present invention relates to barges and, more particularly, to barges comprised of a plurality of a modular float sections, assembled by drawing them together from a spaced array, and releasably secured one to the other through separable alignment pins and post tensioning cables.
2. Technical Considerations and Prior Art
The provision of flotation platforms and barges which may be constructed in modular form, greatly facilitates activities such as drilling for oil in offshore areas. These flotation units are generally comprised of a plurality of smaller flotation elements, transportable to a select assembly site for securement together through a substantially rigid structural network. The float elements, or modules, are usually linked by connecting adjacent structural points of contiguous ones. Such a manner of construction forms an arrangement which is suitably rigid for the support of drilling rigs in ocean areas.
The fastening means for each float at the structural interconnect has formed the basis for many improvements in modular barge construction. For example, certain latch configurations have been shown to freeze up due to temperature, corrosion and/or build up of marine life. It has been found that such modular barges can be readily assembled through the usage of mating male-female elements in the form of pin-sockets correspondingly formed in each modular section. Spacing of these male-female fasteners vertically about the sides of the modular sections has been shown to provide adequate structural integrity and a variety of assembly advantages.
Application of male-female elements for flotation bodies is, however, not limited to modular barges or platforms. Modular constructions of ships and related powered vessels have utilized such fastening means to removably connect two complemental sections in abutting relation, capable of detachment if one should become damaged. In such constructions, both separable and integrated coupling elements have been used to connect the abutting sections for quick disconnect. Separable elements have included tubular, tapered sections. Integrated elements have included fixed and extendible locking projections adapted for engagement with the mating module. Generally, however, alignment and assembly upon ice and/or open seas has not been a design criteria in this area.
Male-female connections on modular platforms adapted for oil well drilling have generally utilized the integrated coupling elements, with design emphasis on their alignment and assembly in water. For example, one variety of platform barge utilizes fixed connecting pins spaced around the module in vertical pairs. Such structures have been shown to facilitate assembly at sea while exhibiting sufficient structural integrity. These constructions although substantially rigid, are subject to high stress concentrations in the fasteners and ultimate yielding when subjected to various loading forces as is common by wind and waves or when assembling upon ice. Such supporting surfaces often produce twisting and turning forces and relative interaction between adjacent modules during and after assembly. Such conditions aggravate the already difficult task of uniting the plurality of floating elements as well as keeping them intact.
When modular elements are assembled upon ice packs, subject to fracture and breakthrough, it has been shown that fastening projections integrally formed in a first module, regardless of taper and size, can hinder rather than aid the overall assembly process. For example, fastening projections formed as tubular extensions engageable in female recesses of the adjacent module, are subject to deformation when one module rises or falls in relation to the other. Once distorted a complete module may be rendered in-operative for assembly as long as the fastening projection is not engageable. Once latched together, if such a rigid projection becomes deformed, disengagement may be dangerously hindered.
The assembly of modular platforms upon ice and on rough seas is further aggravated by the difficulty in positioning the heavy modules together and attaining the necessary degree of alignment therebetween for fastening. Heavy cranes and equipment are often used to accomplish this. When tubular male projections are employed, they be partially tapered to aid in the initial union with the adjacent recess. However, even when the projection is tapered the problem of moving the modules together so as to not damage the appendages still remains. When the assembly location is thin ice or open seas, this aspect becomes the dominant assembly criteria of module design.
Further complicating the design considerations for modular barges adapted for ice regions, such as North Sea areas, is the problem of the assembled barge freezing in the ice. The problem is of course recognized when disassembly of a barge floating in an ice pack is attempted. The peripheral modules can often be broken free from the ice simply by unloading the barge and allowing the bouyant force of the water to raise it. However, standard male pin connections require relative lateral movement between modules for disassembly, which is generally blocked by the abutting ice. Such conditions may thus necessitate special disassembly apparatus.
It has been shown that flexibility must be afforded in the fastening means of the adjacent modules for both assembly and disassembly. Furthermore, means for the drawing together of the modules one to the other upon uneven, fragile or undulating surfaces, wherein alignment may be readily accommodated, has been shown to be necessary. Such conditions render the usage of fixed, tubular projections less than an optimal design. Furthermore, such projections create hazards in transportation occuring during the necessary transport of the individual modules by airplane.
It would be an advantage therefore, to avoid the problems of prior art modular barge structures of the type which may be handled and transported conveniently and safely by airplane, by providing them with separable alignment and coupling elements and related apparatus facilitating the linking, alignment and securement of the array of flotation modules into a structure which facilitates assembly and disassembly upon rough seas or ice and provides means for shear stress and strain relief between adjacent modules without the deformation and damage thereof.